In the process of establishing an oil or gas well, the well is typically provided with an arrangement for selectively establishing fluid communication between the interior of a tubular string, such as a casing, a liner, a tubing or the like and the annulus surrounding the tubular string. One method for establishing such communication is through the use of explosives, such as shaped charges, to create one or more openings through the tubular string. The shaped charges typically include a housing, a quantity of high explosive and a liner. In operation, the openings are made by detonating the high explosive which causes the liner to form a jet of particles and high pressure gas that is ejected from the shaped charge at very high velocity. The jet is able to penetrate the tubular string, thereby forming an opening.
The process of perforating through the casing dissipates a substantial portion of the energy from the explosive perforating device and the formation receives only a minor portion of the perforating energy. Further, explosives create high-energy plasma that can penetrate the wall of the adjacent casing, cement sheath outside the casing, and the surrounding formation rock to provide a flow path for formation fluids. Unfortunately, the act of creating a perforation tunnel may also create some significant debris and due to the force of the expanding plasma jet and drive some of the debris into the surrounding rock thereby plugging the newly created flow tunnel.
Moreover, as hydrocarbon producing wells are located throughout the world, it also has been found that certain jurisdictions discourage or even prohibit the use of such explosives. In these jurisdictions and in other locations where it is not desirable to use explosives, mechanical perforators have been used to establish communication between the interior of a tubular string and the surrounding annulus.
It should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward and the like are used in relation to the illustrative embodiments as they are depicted in the figures. Where this is not the case and a term is being used to indicate a required orientation, the specification will make such clear. Upstream, uphole, downstream and downhole are used to indicate location or direction in relation to the surface, where upstream indicates relative position or movement towards the surface along the wellbore and downstream indicates relative position or movement further away from the surface along the wellbore, unless otherwise indicated.
Even though the methods herein are discussed in relation to a vertical well, it should be understood by those skilled in the art that the system disclosed herein is equally well-suited for use in wells having other configurations including deviated wells, inclined wells, horizontal wells, multilateral wells and the like. Accordingly, use of directional terms such as “above”, “below”, “upper”, “lower” and the like are used for convenience. Also, even though the discussion refers to a surface well operation, it should be understood by those skilled in the art that the apparatus and methods can also be employed in an offshore operation.